Hydraulic jack.



Patented Aug. I2, |902.

. L. S. PITCHER.

HYDRAULIC JACK.

(Appliation led Mar. 29, 1902.) (No Model.)

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UNTTEn STATEs` IPATENT QEEICE.

LEwIs s. PITCHER, on ALBANY, NEw YORK, A'ssIeNoR To WILLIAM M. DUDeEoN, EXEoUToR oF Eroi-IARD DUDeEoN, nEcEAsED.

HYDRAULIC JACK.;` l

srEcIFIcATIoN forming par@ oftewel-s Patent No'. 706,850, dated August 12, 1902.

Application filed March 29, 1902. Serial No.1001553. (N0 mOdL) To {If/ZZ whom, it' 'litri/,y concern.'

Be it known that l, LEwIsS. PITCHER, a

-citizen of the United States, and'aresident of Albany, in the county of Albany and State of New York, have invented a Ycertain new and useful Improvement in Hydraulic Jacks, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, in which- Figure l illustrates a Vertical sectional view of the parts embodying the invention. Fig. 2 illustrates a-sectional viewof the loweringvalve in its normal position. Fig. 3 shows a View the same as Fig. 2, the lowering-Valve being forced oif its seat, as during the act of lowering. Fig. 4t' 'shows the lowering-Valve when in its position of greatest depression, acting as a check to prevent accident. Fig. 5 shows a modified construction.

The purpose of this invent-ion is to so construct the lowering-valve of'hydraulic jacks 4as to preclude the possibility `of accident or fracture of the load by ignorant or unskilful manipulation of the jack. Hydraulic jacks are used under greatly -differing circumstances and frequently in the hands of persons who do not understand the construction. of a hydraulic jack nor the principles involved in their operation nor vthe danger to the load carried by the jack nor the danger of serious accident, event involving loss of life, which may result from improper manipulation during the lowering operation, which is a much more hazardous proceeding than that of lifting.

In the drawings hereof I have illustrated those parts only which are involved in the invention. It willV be understood that the jack in question is supplied with the ordinary pumping and lowering lever and that the piston of the pump is suitably connected therewith. These parts are. so well understood that illustration or description thereof is not necessary.

Referring to the drawings, A illustrates the base of thejack; B, the cylinder; C, the ram; D, the pump-block; E, the pump-bore; F, the piston; G, the piston-valve; H, the bonnet for the piston-valve; I, the packing; J, the lowering-valve block; K, the bonnet for the lowering-Valve 5 L, the spring which normally M, the loweringup its sides, and, third, the upper cylindrical i part M3, which tits snugly within the cylindrical boring M4, madeV in the bottom of the pump-block D.V Through the pump-block there are bored a series ofv openings N N, which'connect with an opening O in the lowering-valve block, and thence through the bonnet L and the openings P therein to the force-chamber Q of the jack. The arrangement and dimensions of these parts are such that when the lowering-valve is in the position shown in Fig. Z-that is to say, is against its seat R-no liquid can pass from the forcechamber upwardly. Thus the `load may be held permanently in its then position, whatever that maybe. Whenit is desired to lower the load, the lever is manipulated in a manner well understood and the piston F depressed until the bonnet H on its lower end presses against the upper end of the loweringvalve, as shown in Fig. 3, whereby it is depressed gradually and smoothly, so that the valve M is forced off'its seat' sufficiently to permit the liquid to escape from the forcechamber upwardly through the bonnet K,

passing through the now open valve-seat R upwardly through the passage O and thence through the passages NN into the pump-bore and thence in a manner well understood back again to the reservoir in the head of the jack.

ln the hands ofa skilful operator the abovestated depression Vof the piston and the forcing of the lowering-'valve off its seat will be done with a strong firm slow movement, so that the lowering will be effected smoothly, easily, and continuously; but in the hands of an unskilled person the lowering is frequently effected by a strong sudden movement of the pumping-lever, so that the lowering-valve is thrust off its seat quickly and to its fullest extent, whereby the liquid in the force-charnber is instantly released to its fullest capacity, which immediately results in a sharp deeline of the load attended by a violent jerky impulso heilig conveyed to the load and great IOC) strain applied upon the jack. If the load be ofa frangible nature, such as alocomotive or many forms of machinery, or if it have great inertiasuch as a building, particularly of brick or stone-then the vibration thus engendered almost inevitably results in the fracture of some part of the load and frequently in breakage of the j ack itself, sometimes even resulting in loss of life. In order, therefore, to prevent vaccident resulting from unskilful handling, I so construct the parts that if the above-stated excessive downward movement is suddenly applied to the plunger then the parts will be carried into the position shown in Fig. 4c, in which the lowering-valve is shown at its lowest position and in which the cylindrical part M3 of the lowering-valve has passed clear across the mouths of the passages N N and effectually cut off the passage of liquid through them, so that the lowering operation is arrested. Consequently in the hands of an ignorant or unskilful operator'the sudden depression of the loweringvalve to its fullest extent can have no serious results, because all that will happen will be a momentary shivering in the load during the time the part M3 of the lowering-valve is passing the mouths of the passages N N. Thereupon the lowering action will at once cease and opportunity will be given for a more skilful person to be called to the lever. Thus in manyinstances accident and fracture will be avoided.

In Fig. I show a modified construction in which the passages N connect with trans- Verse passage NQ made in the lowering-valve block and which connect with the channel O. The advantage of this construction is that when the passages N connect diagonally with the passage O their mouths necessarily have considerable vertical area, whereas if the transverse passages N' Nl are employed the mouths are or may be ofless vertical dimension. Thus the necessary transit of the lowering-valve, or, rather, the section M3 thereof, to cut off the backflow of the liquid will be greatly reduced.

It will be obvious to those who are familiar with this art that modifications may be made in the details of construction of the parts without departing from the essentials of the invention. I therefore do not limit myself to such details.

Having described the invention, I claiml. In a hydraulic jack the combination of a ram provided with a passage-Way connecting the force-chamber of the jack with the bore of the pump, backliow-openings connecting the bore of the pump with the passage-way, a lowering-valve having an upper part adapted to fit the passage-way and move through it to close the backiiow-openings, the upper end of Whichlvalve extends into the bore of the pump sufficiently to enable the piston to depress the valve far enough to close the backflow-passages, a reduced stem past which the liquid can flow, a valve-head below the reduced part of the stem and sufficient space below the head to permit the stated downward movement of the valve, for the purpose set forth.

2. In a hydraulic jack the combination Vof a ram provided with a passage-way connecting the force-chamber of the jack with the bore of the pump, backiioW-opeuings extending from the bore of the pump and connecting at substantially right angles with said passage-way, a lowering-valve having an upper part adapted to iit the passage-way and move through it to close the backflow-openings, the upper part of which valve extends into the bore of the pump sufficiently to enable the piston to depress the valve far enough to close the backow openings, means for permitting the liquid to flow past the stem of the valve, a valve-head at the lower end of the valve and sufficient space below the head to permit the stated downward movement, for the purpose set forth.

3. In a hydraulic jack the combination of a ram provided with a passage-way connecting the force-chamber of the jack with the bore of the pump, backiiow-openings connecting the bore of the pump with the passage-way, a lowering-valve having an upper part which extends into the bore of the pump and which is adapted to fit the passage-way and move through it to close the backtiowopenings, the upper end of which valve extends into the bore of the pump sufficiently to enable it to be depressed far enough to close the backow-passages, means for de pressing the said valve, a reduced stem past which the liquid can iiow, a valve-head below the reduced part of the stem and suiiicient space below the head to permit the stated downward movement of the valve, for the purpose set forth. v

Signed at the city of New York this 26th day of March, 1902.

LEWIS S. PITCHER. Vitnesses:

PHILLIPS ABBOTT, F. M. DoNsBAcH.

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